Estimation of transfer rates

The Frenkel component is crucial in assisting nonelastic relaxation whereas the cavity component obviously shows the large radiative width of this branch. Let us recall that the order of magnitude of the photon lifetime is for 1 — R = 

(a) Dispersion curve for cavity polariton and energy relaxation of Wan-nier-Mott excitons (b) coupling coefficient of the lower branch to cavity photon and to exciton. 

To calculate the nonelastic transition rate k, p = 1 — k, p we use Fermi s golden rule 

If the exciton-phonon coupling in organics is dominant we can neglect in eqn (13.113) the contribution of exciton-phonon coupling in semiconductor QWs. Then to populate the states of branch p = 2 with large radiative width (i.e. states with small k 0.2 kcav, see Fig. 13.14c,d) we assume a dominant, resonant, intramolecular phonon to play the main role so that 

Energy relaxation of Wannier-Mott excitons when coupled by the cavity to Frenkel excitons in an organic quantum well. The vertical arrows represent inelastic scattering of Wannier-Mott excitons to Frenkel excitons. For simplicity, possible changes in k are omitted. Reprinted with permission from Agranovich et al. (66). Copyright Elsevier (1997). 

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